The plane that crashed and burst into flames in Madrid reported an air intake gauge overheating before a first attempt at take-off but it was not clear if this was a factor in the disaster, which killed 153 people, owner Spanair said on Aug. 21.

The airline said it has not yet determined the cause of Aug. 20's crash, the nation's worst aviation accident in nearly 25 years. Only 19 people survived, among them three of the 22 children listed as passengers.

Spanair spokesman Javier Mendoza said an air intake temperature gauge under the cockpit had detected overheating and technicians corrected the problem by turning off the gauge.

Mendoza said the device is not on a list of equipment that has to be functional for a plane to take-off.

Spanair says the plane was eventually cleared by company technicians before it crashed on its second attempt to take-off for the Canary Islands.

Mendoza said the MD-82's two black box recorders have been recovered but one is damaged.

Alvaro Gammicchia, an Iberia pilot who has flown MD-82s for seven years and represents the pilots' union SEPLA, said that even without the valve working "the plane would not fail to the point of causing a tragedy."

The Spanish newspaper El Pais reported that one of the two engines failed and may have caught fire during take-off.

Another paper, La Vanguardia, said witnesses saw the plane's left engine explode and catch fire before the aircraft went down.

Spanair confirmed on Aug. 21 that another of its MD-82s was forced to make an emergency landing on Aug. 16 on a flight from Lanzarote in the Canary Islands to Madrid because of problems with both of its engines.

The plane landed in the nearby island of Gran Canaria, the destination of Aug. 20's flight.

The airline said the pilot of the US-built MD-82 airliner was taxiing for take-off when the gauge problem was detected.

During a second take-off attempt, the plane crashed at the end of the runway, burning and largely disintegrating.

In Washington, the National Transportation Safety Board (NTSB) said it will send a team of investigators to assist.

Spaniards were shocked and grieving for the large number of children feared lost. At least 22 youngsters - including two babies - were among the 172 people on board.

Three are known to have survived the crash.

A passenger list released by Spanair shows that many on board the flight were families - mothers and fathers, brothers and sisters, sons and daughters - many on their way to a summer holiday in the Canary Islands, a popular Spanish beach resort off the coast of West Africa.

The list of passengers includes at least three sets of what appear to be young siblings or relatives.